Electrically operated driving device



O 1934- F. DURING ET AL 1,978,700

: I ELBCTRICALLY OPERATED DRIVING DEVLCE I Filed Nov; 27. 19:51 5Sheets-Sheet 1 Knmd. F5411- Oct. 30, 1934. F. DURING ET AL 1,973,700

ELECTRICALLY OPERATED DRIVING DEVICE Filed NOV. 27. 19551 5 Sheets-Sheet2 0a. 30, 1934. D6R|NG ET AL 1,978,700

ELBGTRICALLY OPERATED DRIVING DEVICE Filed Nov. 27. 1931 5 Sheets-Sheet3 Get. 30, 1934. k F. DURING ET AL 1,973,700

ELECTRICALLY OPERATED DRIVING DEVICE Filed Nov. 27, 1931 5 Sheets-Sheet4 I 6' I I I Zu 17 @L5 7 4 all In fiT-LIETS Ff'fi'i During Konrad M1111:1"

Oct. 30, 1934. FT. DURING El AL ELECTRICALLY OPERATED DRIVING DEVICEFiled NOV. 27, 1931 5 Sheets-Sheet 5 H H Q 13L U 1 H. n F J W 6 I.

Inuun nrs F171? During Konrad Muller impulse senders,

0 magnets Patented Oct.- 30, 1934 UNITED STATES PATENT OFFICE 1,978,700ELECTRIOALLY OPERATED DRIVING DEVICE Application November 27,

1931, Serial No. 577,672

In Germany December 1, 1930 8 Claims.

The subject of the present invention relates to a device driven by anelectric motor, particularly for instruments used in telephone systems,for example rotary switches, signalling devices,

remote repeaters of pointer positions, etc. and the object is mainly toimprove the drive heretofore used in such instruments.

In most of the driving devices for instruments of the above named typeheretofore used electroare generally employed to drive the armaturewhich actuates toothed wheels by means of pawls, the toothed wheelsbeing connected to the setting units (for example, switch wipers,pointers or the like). This type of drive, due to the hard knocksoccurring, possesses various disadvantages, for example, heavy wear andtear of the driving members, weak or reduced setting speed, greatvibration of the instrument members and a generally noisy operation. Theelimination of these difliculties-generally known in the trade has beenattempted in various manners and ways.

It has, for example, been suggested to replace the oscillating movementof the power transmitting means by a rotary movement, making use of atype of electric motor having a rotatable armature instead ofelectromagnets, stopping pawls and the like. The movement of the settingunit which, in many cases, is required to be step-like in nature hasbeen achieved by the al-- ternative energization of two stator coils(for example by means of impulses from an impulse sender (causing thearmature to execute a stepping movement), whereas an uninterruptedrotary movement was obtained by a type of relay interrupter bymeans ofwhich a rapid sequence of impulses have been sent through the two statorcoils. It will be readily appreciated that such a drive is comparativelyexpensive and unfavourable in technical regard due to the fact that aplurality of relays have to be used. In addition to these disadvantagesit should be mentioned that in spite of using an almost continuallyoperating drive it is possible to obtain only a slight increase in thesetting speed by this type of drive.

In order to obtain a greater setting speed, other methods have alreadybeen suggested, including the method of replacing the forward motion ofthe setting units (for example the switch wipers) operated step by stepby means of stop pawls, by a continuous movement which is obtained by apower storer, for example, a tensioned spring and not by anelectromotor. This spring used, for example, in electric switching unitsruns with great speed over the contact laminations until the movedmember is stopped by means of stopping units, such as for example, droppawls, friction or the like when the required contact has been reached.The charging of the power storer, i.e. the tensioned spring is generallyeffected by means of an electromagnet. This type of drive also possessescertain disadvantages although great setting speeds are obtainedthereby, the disadvantages mentioned being a great strain on thematerial and wear and tear and also the mechanical assembly of suchswitching units being too expensive and complicated.

Another generally used type of drive for instruments of theabove-mentioned type are electric motors which by means of a coupling(generally electromagnetically operated) are partly coupled to thesetting units, with the result that a de-coupling of the driving motoris necessary to bring the setting units to rest. The use of couplings,however, has the disadvantage, be-

sides being expensive, that the exact setting of the setting units tothe required positions is not always ensured due to the acceleration ofmass and are also considered unfavourable from a technical point ofview.

The stepping operation cannot even in this case be effected withoutstopping pawl mechanisms so that this combination of drive (electricmotor and stopping pawls) is uneconomical and has the above mentioneddisadvantages associated with stopping pawl drives.

For the purpose of eliminating the above men tioned difiiculties anelectric motor according to the invention is used to operate instrumentsof the above mentioned type, the rotating member of the said electricmotor actuating switching means for the control of the motor windingsand bringing the switching means to rest by generating a staticelectromagnetic field. The motor can also be designed as a motor with anarmature having no windings or as a motor with i by the rotating motorflux. The switching means for the control of the energizing winding areso designed. that an automatically controlled rotary movement 'ispossible as well as a stepping movement of the armature (for example,caused by impulses). In such a case the stepping movement of the motorarmature can either be controlled by impulses arriving from the outsideor by means of impulses controlled by the motor.

The continuous or nearly continuous rotary of the armature can also beobtained, example, by means of movement by various means, forcollectors, by means of cam contacts operated members which influencethe magnet windings of the motor and by means of brush wipers operatedby the movable motor member brushing stationary circular segments or invarious other manners known per se.

According to the invention such switching means have been foundparticularly suitable in which the brush points are arranged separatefrom the contact known heretofore for the control of motor windingsconsist exclusively of brush wipers running over the collectorlaminations, brush carbons or the like, that is to say, consisting ofarrangements in which in addition to the mechanical wear and tear at thebrushed points, also the wear and tear caused by sparks is apparent asthe brushed points at the same time serve as conductors for the current.For this reason the switching means for the control of the motorwindings according to the invention are suitably designed in the form ofa set of contact springs which are mechanically controlled by therotating motor member. murder to avoid the sparks generated at theswitching points which considerably reduce the efiect of the motor,suitable means for example, condensers, chokes or the like are provided.

; As a heavy starting and stopping moment is required for a staticmagnetic field to cause a stoppage for the-above mentioned purpose, thestationary as well as the rotating armature poles according to theinvention are circular instead or square or rhombic. Such a constructionof the poles is particularly advantageous in motors having armatureswith no windings as, due to the faults in the winding, considerablepower can be generated only if all possible means for the increase ofpower have been taken into consideration.

Further details of the driving device according to the invention areillustrated in the drawings and explained in the description below inconjunction with embodiments and particularly suitable circuitarrangements, especially for switching devices. Fig. 1 shows anembodiment of the invention for a rotary switch as used in telephonesystems.

Fig. 2 shows a circuit example for the rotary switch shown in Fig. 1.

Fig. 3 shows an electric motor with an armature without windingsconstructed according to the invention.

Figs.- 4, 5 and 7 show an example of a motor armature having anauxiliary armature, while the circuit associated with this motor isshown in Fig. 6.

' Figs. 8 and 9 show an embodiment for a motor which operates as analternating current motor during the uniform operation.

Fig. 16 shows a motor in which the uniform points. Switching means runas well as the stepping operation is effected over one and the samecollector.

In Fig. 11 a circuit arrangement is shown in which the device driven byan electric motor according to the'invention is utilized to operate aswitch for telephone systems.

The contact bank 1 of the rotary switch shown in Fig. 1 is brushed bythe switch wipers 3 arranged on the shaft 2. The drive of the switchwipers is eifected by means of the toothed wheels ;4, 5 and 6, by thearmature '7 of the motor, the stationary stator armature 8 of which isenergized by the winding 9. It will be seen from the circuit shown inFig. 2 in which manner the motor is built to operate with a uniform oralmost uniform as well as a stepping motion. For this purpose two relaysare provided, namely, a reversing relay U and. an impulse relay J. Theoperation is as follows: closing the contacts 21!. and 4u'of thereversing relay U starts the motor as, due to a stopping arrangement notshown inFig. 2, corresponding to the stopping arrangement shown in Fig.3, retaining the armature in such a position that a rotary moment caneffect it. The motor runs uniformly or ahnost uniformly due to thecollectors represented by the reference numeral 11. By switching over tothe contacts lu and 3a the brushes allocated to the collector 11 aredisconnected from battery and thus the brushes of the two brush rings 12are connected up to which the ends of the armature winding areconnected. The result is .that the armature will be permanentlyenergized from abattery B and is stopped in position by means of thestatic field generated by the stationary portion of the motor. Thecurrent in this case extends from battery B over the closed contacts 6iand la, collector brush, brush ring 12, armature winding and back to theother brush ring 12, collector brush, contacts 3a, 82', and back tobattery. The static field is generated by winding 9 and battery B due tothe closing of contact 13. The batteries B and B, of course, may be oneand the same source of current supply. A succeeding impulsiveenergization of relay J causes the current direction in the armature ofthe motor to be reversed, with the result that individual steps in tunewith the energization of the J-relay.

The armature of the motor shown in Figure 3 has no For rotating in onlyone direction it is provided with projections 17. This motor operatescontinuously by the alternating energization of magnets '14 and 15.These magnets 14 and 15 have counter poles 31 and 32. The stoppingarrangement consists of two flat springs 19 and 20 which rest against asquare 18 disposed on the shaft of the armature. On the armature shaftare in addition two interrupters 21 and 24 the member 22 of which'is ametallic conductor for electric current and the member 23 of which is anon-conductor. The brushes 25, 26, 33 and 34 slide on theseinterrupters: During continual operation the current from the batterytakes the following path: earth, battery 30, winding of magnet 15,interrupter segment 22, collector brush 33, contact 29, earth. Thewinding 15 is therefore energized,

and attracts the armature 16. After a revolu- 1 tion approaching 90degrees the brush 33 leaves segment 22 while at the same time the brush34 runs on to segment 35 of the interrupter below, thus energizing thewinding of the magthis takes net 14 in the following circuit: earth,battery 30, winding of magnet 14, interrupter segment 35, brush 34,contact 29, back to earth. The current is fed to the interruptersegments 22 and 35 in known manner, for example, by means of a brushring. The motor thus runs evenly or almost evenly as long as the contact29 is closed. By the opening of contact 29 and the closing of contact28, the one type of movement (continuous movement) is changed into theother type of movement (stepping movement). During the latter type ofmotion the collector brushes and 26 will function. These brushes 25 and26 are set at such an angle relative to the brushes 33 and 34 that theconnecting up of the second stator coil 14 to be energized cannot takeplace when the armature is located in front of the pole of the firststator coil 15. According to Fig. 3 the current, after closing contact28, takes the following route: earth, battery 30, winding 15,interrupter segment 22, brush 25, contact 27, contact 28, back to earth,with the consequence that the stator coil 15. is energized and thearmature 16 revolves until set in front of the pole of the coil 15.After the opening of contact 27 the coil 15 will be disconnected frombattery, whereupon the armature, under the influence of the stoppingarrangement 18, 19, 20 advances to such an angle that the segment 35 ofthe interrupter 24 will come into contact with the brush spring 26.Hereby a circuit for the coil 14 is prepared so that, at the closing ofcontact 27 the coil 14 is energized instead of the coil 15 and thearmature will be drawn as far as in front of the pole of the coil 14.This operation is repeated as long as impulses are passing through themotor by contact 27 being actuated. To ensure that the armature 16rotates in correct direction it is fitted with projections 17 in amanner known per se. Between these projections and the actual armaturepole of the armature 16 portions 36- have been cut out in the iron inorder to ensure that the armature is securely retained in front of therespectively energized pole.

Figs. 4, 5, 6 and 7 show an embodiment for a motor provided with a mainand an auxiliary armature. Between the diagrammatically shown statorcoils 33' and 34 the main armature 35 rotates and ismade of sheet metalhaving a cross section in the shape of a double T in order to reduce itsmass to the greatest possible extent. This main armature 35 is alsoprovided with projections 38. By means of the spring37 an auxiliaryarmature 36', likewise arranged'in the magnetic field of the poles 33'and 34', is provided on the armature shaft 45, the said auxiliaryarmature 36 being rotatably pivoted on the shaft 45 by means of thebearing sleeve 46. The mass of this auxiliary armature is keptexceedingly low compared to the mass of the main armature. The fibredisc 40 is rigidly connected to the shaft whereas the fibre disc 39 isrigidly connected to the bearing sleeve 46. The contact springs 41 and42 are actuated by these fibre discs. A stopping arrangement similar tothe type shown in Fig. 7 is also fitted on the shaft 45, the saidstopping arrangement comprising an arresting spring engaging in thenotches 46' of the arresting disc 49. Thenotches 46 are so arranged thatthey operate when the armature 35' is disposed immediately in front ofthe poles of the motor. The object of this stopping arrangement is toretain the main armature35' in its position in front of the poles whenthe auxiliary armature 36' is set to a dellnite angle under the actionof the. spring 37 when the stator pole is disconnected from the'battery.

In conjunction with the circuit shown in Fig. L

6 the operation of the motor will be explained.

The motor shown in this figure has two stator coils, each provided witha pair of poles similar to the arrangement shown in Fig. 3. In theposition of the contact U47, as shown in the illus- 1 tration, the motorruns uniformly or almost uniformly as, by means of the fibre disc 40 thestator coils 52 and 53 are alternatively disconnected from the batteryby the separation of the contact springs 41a and 41b which have beendisplaced about If, for example, the fibre disc 40 is positioned betweenthe pair of contact springs 411), the stator coil 52 will be energizedover the following circuit: earth, U47, pair of contact springs 41a,coil 52, battery 51, earth.

ously connected up by this contact,-whereupon the motor is brought torest by the generation of a static field. The two windings of the motorare connected to battery as follows: (1) earth, contacts U47, 41a, coil52,. battery 51, earth. (2) earth, contacts U47, 41a, 11, coil 53,battery 51, earth.

In order to obtain a stepping movement of the armature the circuit for anot shown control relay U is closed which, for example, may be energizedin conjunction with relay J. Relay U opens its contact U47 and closesU48. By the opening 'of contact U47 the earth potential is disconnectedfrom the motor windings so that they receive no current. No" effect isobtained by connecting the earth potential overcontact U48 as a secondcontact 12 of the now re-energized relay J is opened.

The armature comprises a main and an auxiliary armature similar to thatin the embodiment mentioned above. When the motor is brought to rest bythe closing of contact i1 thearmature will be disposed in front of oneof the pair of poles. The main armature in this case tends to pass theenergized pole pair due to its mass. This, however, is of no consequenceas the switching means 41a, 41b, which it actuates are disconnected. Theauxiliary armature, on the other hand, is securely held in front of thepair of poles due to the smaller mass. The main armature after havingoverrun is positioned by the static field in front of the pair of poles.In this position of the main armature the spring 50 snaps into the notch46 of the fibre disc 49 and thus retains the main armature in thisposition.

When the energizing circuit is disconnected which, as above mentioned,is caused by contacts U47 and ii, the auxiliary armature proceeds tosuch an angle under the influence of the helical spring 37 that one ofthe two sets of contacts, for example; 42b is opened. In this manner thewinding 53 of the stator is preparatoriiy disconnected so that, at aclosing of contact i2 the coil 52 only will function and thus cause thearmato take one step. The circuit extendsoverzearth, U48, contact i2,set of contact springs 42a,

stator. coil 52, battery 51, earth. ,The 0011.52 is .disconnected fromthe battery at the opening of contact j2. The auxiliary armature, underthe actionof the spring 37, revolves so tar-'thatrthe set ofjsprings 42awill be preparatorily separated.

At repeated closing of contact i2 the coil 53 will.

. .1 thereby be energized. As will be seen it is therejiore possible tocause the motor armature to re-' volve each time to an angle of 90 aftercontact U48 has been closed by the intermittent operatlon contact i2.

8. and 9 show an embodiment in which.

the motor for continuous run is driven by alternating current, whereasthe individual steps are be connected up to an alternating currentsource till of supply in the following circuit current source 01 supply,contact in, collector brush 3', armature winding 2', collector brush 4',contacttu' back to the current source of supply. The stator poles 6' and7 are energized from battery'B by the stator winding 1' when contact 8is closed, with,the consequence that the armature willmove continuously.When the U-relay is energized the contacts in and 3a are separated,

whereupon contacts 2a and 4a are closed and the direct current source ofsupply B will be applied to the armature winding over contacts 3i and itwhich causes the armature to be arrested. By the intermittentenergization of the J-relay the current direction of the armaturewinding is changed by means of contacts 2i and at so that the armatureis advancedhali a revolution at each energization. In order to ensurethat this occurs without fail the stopping ar-- rangement shown in Fig.9 is provided which consists of a flat spring 10' provided with a roller11' and also an arresting disc 9' shaped:

like a double heart. I

Fig. 10 shows a further ent in which the polarization of the motorwindings required for the arrest or for the stepp n operation whichdiffers from the polarization which causes the continuous movement andis efiected by switching means which cause the motor to move uniformlyor almost uniformly. These switching means comprise-an ordinarycollector having two pairs of collector brushes, the second arrotbrushesbeing arranged at a certain angle'in relation to the first pair ofbrushes. The

brushes 13' and 14' operate during continuouswhereas the brushes 12' and15' cause the motor to stop or run step by step. It contacts 111." and3a" are closed the motor will run as an ordinary direct current motorwith wound armature. 11 contacts 11!." and 3a" however are separated atthe energization of relay U and thus contacts 2u"'and 4a" are closed,the pair of brushes 13' and 14. are disconnected from battery and thusconnect up the brushes 12 and 15' which are arranged above the polealternator laminations 16' and 17 in such a manner that ade-polarization of the armature 5' will not occur atthe right momentwith the result that the armature remains stationary under the infiuenceof the field of the stator poles 6 and '1'. In a similar manner, asalready described in the above, the armature is disconnected from thebattery at the opening of the J-contacts but advances, however, to acertain angle under the action of a not shown arresting arrangement, 1

rotating half a revolution at each closing of the J'-contact.

In Fig. 11 a circuit arrangement is shown in which the device driven bythe electric motor 'necessarycomponents for theunderstanding of theinvention are shown, whereas all devices having no connection with theinvention. for

example, devices for the transmission of signals .(i-ree or busysignals, ringing, etc.) have been omitted. r

This case mainly relates toa so-called rotary switch (similarto that inFig. 1) that is to say,

a switch having'a direction of movement at which the individual leadsare readily reached by the rotary movement of the switch wipers. As suchswitches must operate with great speed,

the device driven by an electric motor-according.

'3a. After the preceding switches have completed their operations theimpulse relay A will be energized over: earth, battery, resistance Ws'i,b-lead, loop in thepreceding switch, a-lead, winding of relay A, earth.Relay A opens its contact 3a whereby the above mentioned short circuitfor relay C will be removed. This causes relay C to be energized,whereupon it opens its contact 1c and by closing oiits contact 2cprepares the energization oi relay ii. If new the calling subscribersends out number impulses, thereby causing a periodic opening oi theloop extending over the a and b, relay A will be energized according tothe. impulses sent out. At the first release of relay A, contact 3a isclosed with the result that relay V is one in the following circuit:earth, contacts so, 2c,

winding I of relay V, battery, earth. Relay V remains energized duringthe whole impulse series as its contact 321: short-circuits its secondwinding causing the relay to be so retarded in its operation that itdoes not release during the short current interruptions at contact 3a.In consequence hereof the contact 201) and consequently also thestarting circuit for the motor is closed during the impulse series over:earth, contacts 200. 19a, 6p2, contact at DL, motor winding M011,battery, earth. The devices DL and ES are only diagrammatically shown inthis case. They correspond to the switching devices be applied. Whenrelay A releases for the first (shown in Figs. 2 to 10 for the controlof the motor windings in order to obtain a continuous time and contact16a is closed, the following bridge is formed after relay V isenergized, for the motor coils: motor coil MoI, d-wiper of the switch innormal position, O-contact, contacts 181, 16a, 1222, 811, motor coil No.II. The two motor coils are simultaneously energized in the followingcircuits: (1) earth, contacts 201;, 191:, 6:12, contact at DL, motorcoil No. II, battery, earth, and (2) earth, contacts 200, 19a, 6 12,contact at DL, contacts 8a, 120, 16a, 181, O-contact, d-wiper of theswitch in normal position, motor coil MoI, battery, earth. In thiscondition it is impossible for the motor to start but as soon as relay Ais reenergized after the end of the first impulse the bridge at contact16a. which is opened when relay A is energized is broken with the resultthat only one of the motor coils, connected up bya contact at DL, isenergized (the motor coil No. II in the position shown) whereupon astarting moment is applied to the armature of the motor. The armature,as well as the switch wipers connected thereto are thus caused toadvance. Prior to the opening of contact 16a, however, the contact 15ais closed (light contact). The motor, therefore, after the switch wipershave been set to the next contact, immediately comes to rest as thebridge is now reclosed over contact 150, the first main stop lHR and thefirst contact of the contact bank, switch wiper d, and the static fieldreproduced by the simultaneous energization of the two energizingwindings of the motor. It will be assumed that a calling subscriber hassent out an impulse series consisting of two impulses. As alreadydescribed in the above, after the end of the first impulse, the switchwipers are located on the first contact (d-wiperon contact 1BR). If therelay is now de-energized the-second time and contact 15a is opened thebridge of the motor windings is broken at contact 150 with the resultthat the motor starts, as mentioned above.

The switch wipers which are driven with great speed are brought to restwhen the wiper :1 reaches contact lZR (first intermediate stop) andtherefore the bridging of the motor windings has been completedover-this contact and contact 160.. As soon as relay Areturns to itsoperative position after the end of this impulse, the motor is restarted(bridge being broken at contact 16a) and the switch wipers are set oncontact 2HR where the bridgeis reclosed over contact 150.. Relay Vreleases due to the impulse series now being ended and contact 3aremaining open for an extended period. It should be observed that the,device has been so arranged that the contact 250 is closed sooner thancontact 111;. The motor is connected to battery over: earth, contact2112, 22k, (closed when the switch wipers have left their originalpositions) key T3 in normal position, resistance Wi5, contact 6172,contact at DL, motor windings, battery,- earth. The resistance Wi5,connected up in this circuit, is provided for the purpose of weakeningthe current so that the speed of the motor is reduced during thesucceeding hunting operations. The arrangement is so made that theswitch wiper (1 leaves its position 2HR before contact 110 is closed.The hunting for a free line within the selected line group is effectedover the c-wiper of the switch. The switch wipers are advanced until afree line has been found, such a line'being characterized by batterypotential being applied thereto. The first test relay P1 is thenenergized in the following circuit: battery potential of the free line,c-wiper of the switch, contact 37122, winding of relay P1, key T2 innormal position, contacts 3112, 30!, 260, 287:, (closed when the switchwipers have left their normal positions), earth. Relay P1 is energizedand immediately closes its contacts 9p1 and 10111. The two motorwindings are bridged at contact 9p1. By the simultaneous energization-oi. the two windings a static field is generated in the manner fullydescribed above which arrests the motor and also the switch wipers. Thetwo motor windings are now energized as follows: (1) earth, contacts210, 22k, key T3, resistance Wi5, contact 6p2, contact at DL, motor coilMoII, battery, earth, and (2) earth, contacts 211;, 22k, key T3,resistance Wi5, contact 6p2, contact at DL, contact 9p1, motor relayMoI, battery, earth.

By the closing of contact 10p a circuit for the second test relay P2 iscompleted over: earth, battery, motor coil Man or MoI, contact 10121,windings I and II of relay P2, key T2, contacts 311), 301, 260, 28k,earth. The relay P2 is energized and operates its contacts.

The circuit for the energizing windings of the motor is broken atcontact 6122. The circuit for the first test relay P1 is opened atcontact 37112 and the c-wiper of the switch is connected to the secondtest relay P2 at contact 361:2. By the closing of contact 25122 the highresistance winding II of relay P2 is short-circuited, whereby the switchis guarded against a further seizure. By the closing of contact 34122the following circuit is completed: earth, contacts 28k, 260, 30!, 3122,key T2, contact 34122, winding I of relay L, battery, earth. Relay L isenergized, closes a locking circuit for itself at contact 291 and isthus maintained energized during the duration of the connection in thefollowing circuit: earth, battery, winding I of relay L, contacts 291,260, 28k, earth. The final blocking circuit now extends over: batterypotential on the c-lead, c-wiper of the switch, contact 36112, winding Iof relay P2, contacts 35p2, 291, 26c, 28k, earth. Finally the speakingleads to a succeeding impulse receiver are switched through by theclosing of contacts 38p2 and 391:2. 1

When the battery potential is cut of! from the c-lead at the end of theconnection, whereby relay P2 is de-energized, a circuit for the motorwinding is completed over: earth, contacts 51', 6112, contact at DL,motor winding, battery, earth. There being no special resistance locatedin this circuit the switch is rapidly advanced until it has reached itsnormal position. In this position the motor is immediately brought torest as the bridge for the two motor coils is now again completed thus:MoI, d-wiper, o-contact of the contact bank, contact 171, (M011), andthe armature of the motor is held in position by the permanentenergization of the two windings. As soon as the normal position hasbeen reached the off normal contacts 22k and 29k are opened. The earthpotential is cut ofi at contact 211) by means of contact 22k while thecircuit for relay L is opened at contact 28k. Hereby the earth potentialrequired to return the switch to its original position is cut oil by theopening of contact 51. The switch now is set in its original position.

The case will now be considered if all the lines 15 of aselected groupare busy and the switch cannot find a free line during its, huntingoperation. It is again assumed that the impulse series sent out by thecalling subscriber consists of two impulses. The d-wiper of the switchis then brought to rest on contact 2HR in the manner described above.The hunting operation is initiated by the release of relay V and theswitch is advanced by the motor, thus hunting for a free line. Afterhaving passed through the selected line group, the 'd-wiper' finallyreaches contact 3113. The bridge for the two energizing windings of themotor is again set up over this contact as well as over contacts 15a.and 1 31, winding II of relay L, contacts 11v, 8%, etc. with the resultthat the switch cannot advance farther. pleted: earth, contacts 21v,22k, key T3 in normal position, resistance Wi5, contact 6p2, contact atDL, contacts 8a, 110, winding 11 of relay L, contact 13l, 15a, 3HR,d-wiper of the switch, motor coil MoI, battery, earth. Relay L isenergized over its winding II in this circuit and operates its contacts.By the closing of contact 291 a locking circuit is formed for relay Lover winding I of this relay: earth, contacts 28k, 260, 292, winding 1of relay L, battery, earth. The above mentionedbridge for the motorcoils is opened at contact 131, and the return of the switch to itsoriginal position is completed by means of the motor, the coils on whichare now intermittently energized by the earth potential intermittentlyapplied by means 'of contact 52 as already described. Obviously thecalling subscriber in this case may be informed in any known manner bymeans of a signal that all the lines of the selected group are busy.

The switch shown in the embodiment can also operate as a final selector.To this end it will be necessary to operatethe keys represented byT1-T3. The setting to the required line group is effected in the samemanner as when the switch is used as a group selector as described in aprevious paragraph. When relay V releases,

after the end of the last impulse of the first impulse series andcontact 23c is closed at the transmission of the first impulse of thesecond impulse series the following circuit is'completed: earth,contacts 211), 22k, key T3 inoperative position, contacts 23a, 25a,winding of relay U, battery, earth." RelayUis energized in this circuit.At contact 2414, (light contact) it closes a locking circuit for itselfover: earth, battery, winding of relay U, contacts 2411., 260, 28k,earth. The device ES which is so arranged that, at the transmission ofthe impulses for the setting of the switch to a required individual linethe motor advances its armature so far that the switch wipers connectedthereto step from contact'to contact, is connected up at contact 411.,over key T1 in operative position. This device is only diagrammaticallyshown'in Fig. 1 1 similarly to the device DL. A complete description ofthese devices and their operations is furnished in connection with Figs.2 to 10 andthe specification associated therewith, The transmission ofimpulses to ES is effected in the following circuit:

earth, contacts 3a, 20, resistance Wi3, contact 411., key T1 inoperative position, contact at ES, contact 711, motor coil MoII' orcontact at ES (the ofiice contact closed) motor coil M01, battery,earth.

Parallel to the two windings of the motor the devices shown on thedrawings and represented I by C'Oand Wi4, i.e. condensers andresistances,

The following circuit is then comare provided in order to prevent sparkswith their harmful efiects during the run of the motor.

. What we claim as new and desire to secure by Letters Patent is: v

1. In combination with an electric motor of the type in which equipmentis rotated consequent to the alternate energization of a pair of fieldwindings, operating circuits for the field windings including contactsoperable consequent to the rotation of said equipment, a control relayeffective when energized to energize the field windings of the motoralternately under control of certain ones of said contacts totherebyro-' tate the equipment substantially continuously until said relayagain becomes deenergized, and a second relay cooperative with other ofsaid contacts when the first relay is deenergized to rotate saidequipment in a step-by-step manner.

2. In combination, an electric motor of the type in which an armature isrotated consequent to the alternate energization of a pair of fieldwindings, a pair of commutating members rotatable with the armature andeach having a pair of brushes cooperative with one of the field 0windings, and circuit switching means which.- when in one positioncauses one brush of each of said pairs to cooperate with saidcommutating means to rotate the armature of said motor substantiallycontinuously and when in an alter- 5 native position causes the otherbrush set of said pairs to cooperate with said commutating means torotate the armature in steps.

3. In a control arrangement for an electric motor of the type wherein apair of field coils are alternately energized to produce a rotarymovement of the motor armature, the provision of a pair of contact setscontrolled by the armature and included in alternative energizingcircuits of the field windings, the circuits and contact sets being soarranged with respect to said armature that when one set is employed thearmature may be caused to rotate in a step-bystep manner whereas whenthe other set is employed the armature will be rotated substantiallycontinuously, and means for making either contact set efiective. V

4. In an electric motor, a pair offield windings, a rotatable memberrotated thereby, switching means operated by said member to alter natelyenergize said windings to rotate the member, and means forenergizing-both said windings in such a manner as to set up a staticmagnetic field to bring the member to rest in a specific positionrelative to said windings.

5. In an electric motor, a rotatable-membena pair of field windings,means for alternatelylenergizing said windings to rotate said member,means for-always stopping the member'by ener-' gizing both fieldwindings togenerate a static operated position. 1

6. In an electric motor, an armature, field windings for operating thearmature, means for energizing said windings to cause either a con-'tinuous rotary movement of the armature or a step by step rotarymovement thereof, an auxiliary armature, said auxiliary armatureoperated to cause a change from continuous to step by step movement ofthe armature. r

'7. In an electric motor, an armature, field windings for rotating saidarmature, means for energizing said windings alternately to rotate thearmature, an auxiliary armature, said auxilfield to therebymaintainthemember in its last tating the auxiliary armature independent of themain armature, and circuit connections controlled by the auxiliaryarmature for contro the energization of the field windings.

mrrz BORING. KONRAD minim.

